OBSERVATORY

By Henry Fountain

Published: August 16, 2005

Asteroid Hat Trick

Not so long ago, astronomers were unsure that binary asteroids -- two rocks rotating about each other -- existed. But improvements in observational techniques over the last 15 years have removed any uncertainty.

Beginning with the discovery of a companion rock to the asteroid Ida in 1993, there are now more than 60 confirmed or suspected pairs, including 22 in the main belt between Mars and Jupiter. One of those main belt binaries is the asteroid 87 Sylvia, which was discovered in 1866, and a small companion discovered in 2001.

Now, though, it turns out that Sylvia, which is about 175 miles in diameter, has another companion. Frank Marchis of the University of California, Berkeley and colleagues from the Paris Observatory have discovered a second small moonlet, making the Sylvia group the first triple system ever found.

The discovery, announced in the journal Nature, was made last August using the Very Large Telescope array at the European Southern Observatory in northern Chile. The new moonlet is less than half the diameter of the first (4 miles across compared with 11) and orbits Sylvia from 440 miles away, compared with 850 for the first.

Studying the orbits of the two moonlets enabled the researchers to calculate the mass of Sylvia and determine that it is probably a porous agglomeration of ice and rock, what's known as a rubble pile.

The system probably formed through a disruptive collision of two asteroids; the fragments came together to make Sylvia, and other debris coalesced to form the two moonlets. Since Sylvia was named after the mother of the founders of Rome, the two smaller bodies have been named Romulus and Remus.

The Thinking Raven

The term ''theory of mind'' refers to the fundamental ability of a person to understand that other people can have intentions or desires that are different. But does the concept hold for other species? Can a chimpanzee, say, know what another chimpanzee is intending?

The issue is a subject of much debate, and a new study by Thomas Bugnyar and Bernd Heinrich of the University of Vermont is sure to add to the discussion. In a study in Proceedings B of the Royal Society, the two show that ravens know what other ravens have or have not seen.

Ravens store caches of food, which are often pilfered by other ravens who watch while the food is being hidden. In one set of experiments, the researchers allowed a raven that was storing food to see whether another was watching (in this case the second bird was visible to the first but was shielded from the cache by a curtain).

Later, the two ravens were set loose to retrieve the cache. The bird that stored the food behaved differently based on whether the other bird had watched earlier.

A second set of experiments involved two pilfering birds. The researchers found that when retrieving food, a bird that watched the food being cached acted differently if the other bird had watched, too.

Taken together, the researchers say, the results show that ravens are capable of identifying other birds and of knowing what the others had or had not seen. They add that the findings are in line with other work on ravens and crows that shows they have great cognitive potential when it comes to social behavior.

Shrimp That Clean

Among the many oddities of coral reefs are the cleaner fish, wrasse and other species that eat parasites off the skin of other fish in what is generally considered a mutually beneficial relationship. But it's not just fish that do the cleaning: invertebrates like shrimp are known to devour skin parasites as well.

Now, shrimp cleaners have also been found far from coral reefs, in temperate waters. In a report in Biology Letters, scientists from the University of Oslo and the University of Queensland describe cleaning activity by two common species of shallow-water North Atlantic shrimp. The crustaceans removed worms, lice and other parasites from the skin of plaice. The researchers say the shrimp may get some protection out of the deal: there were no attempts by the fish to eat them.

Finding Southpaws in the Wild

It's a right-handed world, as left-handers are quick to point out. For upward of 9 of every 10 people, the right hand is the dominant one.

But what of our relatives, the apes? Particularly our closest cousin, the chimpanzee? Finding evidence that chimp populations show a bias toward one hand or the other could help scientists understand how the difference between the two sides of the brain evolved, said William D. Hopkins of the Yerkes National Primate Research Center in Atlanta.

While such population-level handedness has been shown in captive chimpanzees, many scientists consider the findings suspect. Captive animals are living in humans' right-handed world, after all, which may affect their handedness.

The evidence for wild chimps is even murkier because most studies have involved small samples. ''There is a real chasm between what was reported in captive chimps and what was reported in wild chimps,'' said Dr. Hopkins, who is also a professor at Berry College in Georgia. So a new study by Dr. Hopkins and Elizabeth V. Lonsdorf of the Lincoln Park Zoo and the University of Chicago is groundbreaking. It shows that when it comes to one task -- pursuing a favorite meal, termites-on-a-stick -- wild chimps are predominantly left-handed.

In the study, published in The Proceedings of the National Academy of Sciences, the researchers followed chimps in Gombe National Park in Tanzania as they sought termites. The animals fashion a small stick into a tool by stripping off its leaves and shove it into a hole in a termite mound. The insects climb onto the stick and after 15 or 20 seconds the chimp pulls it out and eats the termites off it.

The researchers analyzed 67 hours of videotape of this termite ''fishing.'' The ratio of left-handers to right-handers was two to one. ''This is almost exactly what we find in captivity,'' Dr. Hopkins said.

Smaller studies of chimp populations in other parts of Africa have shown different handedness traits. For instance, chimps that crack nuts with stones have shown signs of right-hand dominance.

Dr. Hopkins said the difference might be due to the demands of the two tasks: termite fishing requires fine motor control with the fingers, while nut cracking is more of a whole-hand activity. Or it might be a result of genetic isolation of the different populations. Further research will look at these issues, Dr. Hopkins said, and the role that social learning plays in handedness as well.